One thing you should be aware of is that ISBNs can be reused. In theory they shouldn't, but mistakes happen as well as temporary shortages of ISBNs allocated to

One thing you should be aware of is that ISBNs can be reused. In theory they shouldn't, but mistakes happen as well as temporary shortages of ISBNs allocated to publishers. If you want a free and unencumbered source of ISBN data then try the British National Bibliography dataset from the British Library. See http://www.bl.uk/bibliographic/download.html http://www.bl.uk/bibliographic/download.html or browse online http://bnb.data.bl.uk/doc/resource/012877800 http://bnb.data.bl.uk/doc/resource/012877800